The number of collisions that occur every year between vehicles and animals in high risk areas and on open roadways is significant. To reduce the risk of hazardous animal/vehicle collisions, vehicle mounted warning alarm devices of various types including both wind activated alarms and ultrasonic alarms have met with varying degrees of success.
A major drawback to wind activated alarms is that the signals they emit vary in strength and frequency with variations in wind speed and direction and vehicle speed.
Electrically powered ultrasonic alarms will produce sound at a constant frequency regardless of wind velocity and direction or vehicle speed. However, the sound waves that they generate may not carry far enough to adequately alert most animals to the approaching vehicle.